1875.] 425 [Swallow. 



Lustre vitreous like obsidian. Fracture conchoidal. G. 5.755, H. 

 5.5. The characters as determined by the blowpipe corresponded to 

 those given under Samarskite in Dana's Mineralogy. 



Two portions were treated according to the method described by 

 Hermann in the Journal fur Prakt. Chemie, 107 Band (1869), p. 139, 

 which was the latest available research on this mineral. This treat- 

 ment was undertaken in order to ascertain whether tungsten, titanium, 

 thorium and zirconium were present. 



No test was obtained for thorium, and the precipitates which might 

 contain the other elements gave only the reactions for columbic acid, 

 which probably escaped precipitation on account of the degree of 

 concentration of the first solution. These precipitates amounted to 

 only one or two tenths per cent. 



One portion was also treated according to the method given by 

 Dr. Hunt in the American Journal of Science and Arts, Vol. 14 

 (1851), p. 341, in the account of the only analysis of American 

 Samarskite. The mineral was decomposed by sulphuric acid, the 

 columbic acid separated by filtration, all the remaining constituents 

 precipitated by ammonia, and the precipitate so obtained treated with 

 carbonate of ammonia, to dissolve the uranium. The insoluble por- 

 tion was dissolved in chlorhydric acid and the cerium and yttrium 

 precipitated by oxalic acid. But this specimen of Samarskite from 

 Mitchell Co. was decomposed by sulphuric acid with great difficulty; 

 moreover, as Dr. Hunt says, yttrium and cerium, especially yttrium 

 (see Graham-Otto's Chemie, Band II, page 912), are soluble in ex- 

 cess of carbonate of ammonia (although an insoluble double salt soon 

 forms), and the oxalates are readily soluble in chlorhydric acid and 

 the addition of oxalic acid increases the acidity of the solution; there- 

 fore it was deemed best to decompose the mineral by fusion with 

 blsulphate of potash, and to precipitate the cerium and yttrium by 

 oxalate of ammonia before separating the uranium by carbonate of 

 ammonia. 



The analysis given was made on 0.9091 gramme of the powdered 

 mineral which lost nothing on drying at 100°. Another portion 

 weighing 1.07365 grammes gave results which confirm those given 

 below. The analysis by Dr. Hunt and the analysis of a specimen of 

 the same specific gravity from Miask by Hermann are given for 

 comparison. 



